Modern Vulnerability Research Techniques on Embedded Systems

This guide takes a look at vetting an embedded system (An ASUS RT-AC51U) using AFL, angr, a cross compiler, and some binary instrumentation without access to the physical device. We’ll go from static firmware to thousands of executions per second of fuzzing on emulated code. (Sorry no 0days in this post). Asus is kind enough to provide the firmware for their devices online. Their firmware is generally a root file system packed into a single file using squashfs. As shown below, binwalk can run through this file system and identify the filesystem for us.[…]